The purpose of our research program is to study and describe (1) the effects selected drugs can have on the central nervous system of conscious nonhuman primates by studying the effects of these drugs on conditioned behavior in squirrel monkeys and chimpanzees, (2) the effects these drugs can have on heart rate, arterial blood pressure and core temperature in nonhuman primates at doses that have effects on behavior mediated via the central nervous system, and (3) whether the behavioral or cardiovascular effects are altered by other drugs and chemical substances or by behavioral procedures. Our research strategy is predicated on the premise that learned psychomotor behavior is a function of the central nervous system, and changes in the activity of the central nervous system result in changes in behavior. Moreover, drugs and other substances that act on the central nervous system can also affect other physiological systems, including the cardiovascular system and the thermoregulatory system. The laboratory protocols focus on operantly conditioned psychomotor behavior in individual animals as a measure of central nervous system activity, and the direct measurement of heart rate, arterial blood pressure and temperature as indices of cardiovascular and thermoregulatory activity. To obtain the physiological measurements, squirrel monkeys are surgically prepared with chronically indwelling arterial and venous catheters, and direct measurements of blood pressure, heart rate and temperature are recorded and displayed on a physiological polygraph while the monkey is seated in a restraint chair. Depression of a response key positioned on the wall facing the chair-restrained monkey or on one wall of the caged chimpanzee serves as a conditioned response, and schedules of reinforcement arrange consequent events and determine the rate and temporal distribution of responses. The administration of psychomotor stimulants, barbiturates, narcotic analgesics or narcotic antagonists prior to or during the daily behavioral session permits evaluation of the drug effects on the central nervous system and selected physiological systems.